In modern English this would read, ‘It never rains without pouring.’ The meaning is that events, especially misfortunes, always come together.
‘What a day it’s been ‘, sighed Mrs Wood. ‘First I burnt out the kettle, then the electricity fused, then Mrs Mopp didn’t arrive, then the butcher didn’t deliver the meat in time for lunch, then the doctor called and said Tommy’s got measles. It was one thing after another. They say it never rains but it pours.’